Provided are compositions and methods for a high-temperature water-based drilling fluid. More particularly, compositions and methods may be provided for a water-based mud with low solids, high penetration, and stability at high-temperatures.
During the drilling of a wellbore into a subterranean formation, a drilling fluid, also referred to as a drilling mud, may be continuously circulated from the surface down to the bottom of the wellbore being drilled and back to the surface again. Among other functions, the drilling fluid may serve to transport wellbore cuttings up to the surface, cool the drill bit, and provide hydrostatic pressure on the walls of the drilled wellbore. Drilling fluids may be used in high-temperature formations (e.g., formations having temperatures greater than 325° F.) or formations comprising fractures, voids, thief zones, or other such features through which the drilling fluid may be lost. High temperatures may reduce the effectiveness of a drilling fluid to function as desired by reducing the viscosity of the drilling fluid. For example, a drilling fluid may not sufficiently suspend cuttings at higher temperatures. Furthermore, a less viscous fluid may have increased susceptibility to fluid loss through fractures, voids, thief zones, etc. Viscosifiers may be used to impart the drilling fluids with sufficient viscosity to suspend cuttings and mitigate fluid loss.
To remedy these issues viscosifiers may be added in high concentrations to provide sufficient viscosities. However, high temperatures may also reduce the effectiveness of certain viscosifiers, necessitating the need for higher viscosifier concentrations or the use of other materials such as clays. The viscosifiers may be used with clays in order to achieve a desired viscosity or degree of fluid loss control. However, clay may cause severe formation damage by plugging of the pores of the reservoir formation and may also be difficult to clean-up. As a result of these deficiencies, the drilling industry may have increased expenses and downtime, or in some cases, may avoid drilling in certain formations because operations in such formations are not cost effective due to the increased temperature or presence of fluid loss features.